telecom optical networks: the road aheadoptical networks: the road ahead biswanath mukherjee child...

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April 28, 2008 © B. Mukherjee, UC Davis: “Optical Nets: The Road Ahead” (EuroNGI-08) 1

Optical Networks:The Road Ahead

Biswanath MukherjeeChild Family Endowed Chair Professor

University of California, Davis, USA

[email protected]://networks.cs.ucdavis.edu/~mukherje/

Keynote Talk Presented at:4th Euro NGI Conference 2008

Krakow, PolandApril 28, 2008

Telecom


• This is a reduced / redacted version of the presentation given at Euro NGI 2008.

• For more information on some of the materials, please consult my textbook:

Biswanath Mukherjee, “Optical WDM Networks,”Springer, 2006.

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Optical Networks: The Road Ahead

Broadband Access• PONs• WDM in PONs• Long-Reach Broadband Access• Hybrid wireless-optical access• Metro: The vanishing breed?

Backbone Networks• DOCS (“dial for bandwidth”)• Robust Network Design (multi-

layer, multi-domain, multi-path, etc.)

• Ethernet Everywhere-----

• Network Engineering (NE)(vs. TE vs. NP)

• Higher-density switches!

(X)

(X)

Telecom

(X)


Telecom Network Hierarchy

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An Access Network (PON)


System/Network: Value Proposition

Optical ScienceOptical Science& Engineering& Engineering

CurrentCurrentstate ofstate ofthe artthe art

ElectronicElectronic(Computer)(Computer)EngineeringEngineering

SoftwareSoftwareEngineeringEngineering System

VALUE

System ASystem Ax

x

x

x““MyMy”” systemsystem

++Yours too (?)Yours too (?)

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Optical Network Architecture:Extending Our “Boundaries”

Network Architect (Piotr, I, …)

Physical Layer (optical/wireless channel) --materials, devices, subsystems

Applications(“Customer” needs)

+ routing protocols to combat optical channelimpairments

+ breakthroughs needed in device technologies?- optical RAM, ultra-wideband amp, “tunable” AWG, …

Differentiated Services:Bandwidth: OC-192, OC-48, … , STS-1, VT1.5, …Failure-Recovery Delay: The “50-ms myth!”

Network Economics: Pricing, SLA, …


Broadband Access• PONs• WDM in PONs• Long-Reach Broadband Access• Hybrid wireless-optical access• Metro: The vanishing breed?

Backbone Networks• DOCS (“dial for bandwidth”)• Robust Network Design (multi-

layer, multi-domain, multi-path, etc.)

• Ethernet Everywhere-----

• Network Engineering (NE)(vs. TE vs. NP)

• Higher-density switches!

(X)

(X)

(X)

Optical Networks: The Road AheadTelecom

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WDM in PONs (Evolutionary Upgrade)

• Provision Wavelengths as Needed– Distinct growth phases– Upstream/downstream

• Non-Disruptive– Legacy users are unaffected– Infrastructure remains intact

• Maximum Utilization of Capacity– Users are still able to share wavelengths– Shift users requiring more bandwidth

ACK: NSF


• Shifting (exponential model)• λ0 threshold times: 6, 12.5, 19, 25.5-months

WDM in PONs (Evolutionary Upgrade)

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Long-Reach Broadband Access

• Basic Problem– Reach of traditional PON = 10-20 km– Fiber capacity: much larger than data generated by users

served by the limited geography in a traditional PON– Hence Long-Reach (LR) PON should be investigated

• Increase distance to 100 km or more… may need power (so not exactly a “PON”… called “SuperPON” in literature), but use very few active elements... so we call them LR Access Networks

• Sampling of Current LR Access Efforts– ACTS-PLANET; BT Demos; SFI Demos

• Limitations of Current LR Access Methods– “One dimensional” (linear)– Users are located “two dimensionally” on the earth

… so “ring-and-spur” makes more sense for LR Access


Our LR Access Approach

ACK: ETRI Korea

WR

WR

WR

WR

Metro Ring BackboneNetworkAccess Ring

WRWR

WR

Access Ring

WR

WRWR

WR

Access Ring

WR

ONU

WE-PON

ONU

E/G-PON

WDM-PONONU

P1,1

P1,2

P1,3

P2,1

P2,2

P2,3

P3,1

P3,2

P3,3

100 Km

OLT

ONU

ONU

λ1~ λ16

λ1 ~ λ4λ1

λ2

ONU

λ3 λ4λ5 ~ λ9

λ10 ~ λ16

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Hybrid Wireless-Optical Broadband Access Network (WOBAN)

Optimization problem: how far to use fiber? at what point wireless takes over?

ONU

ONU

ONU

Splitter

CO

OLT

AP

Optical backend (PON)Wireless frontend

Wireless routers

OLT

OLT

ONU

Gateway BS

ONU

ONU

ONU

ONU

Splitter

Splitter

Gateway BSGateway BS

Gateway BS

Gateway BS

Gateway BS

Gateway BS

ACK: Nokia (NSN)


Example: WOBAN Front-End Mesh

A part of San Francisco WOBAN (SFNet)

Location:Golden Gate Ave. to Pacific Ave.Divisadero to Van Ness Avenue

Area: 1 sq-mile (approx.)

Population: 15,000 (approx.)

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Wildhorse, Davis, CA: Wireless Routers


Current Deployment Status

Ack: Suman Sarkar

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1 169.237.4.254 (169.237.4.254) 0.973 ms 0.747 ms 0.475 ms

2 169.237.246.238 (169.237.246.238) 0.682 ms 0.797 ms 0.741 ms

3 area2-13--area2.ucdavis.edu (128.120.2.49) 0.880 ms 0.767 ms 0.746 ms

4 area2--area0.ucdavis.edu (128.120.0.133) 0.939 ms 1.295 ms 0.856 ms

5 area0--area14.ucdavis.edu (128.120.0.222) 1.063 ms 1.484 ms 0.887 ms

6 area14--a14.ucdavis.edu (128.120.9.142) 1.009 ms 0.950 ms 0.837 ms

7 a14--ucd-hpr.ucdavis.edu (128.120.9.138) 1.177 ms 1.573 ms 1.173 ms

8 * dc-oak-dc2--ucd-ge.cenic.net (137.164.24.225) 2.901 ms 2.694 ms

9 dc-sfo-dc1--oak-dc2-pos.cenic.net (137.164.22.32) 2.884 ms 2.751 ms 2.655 ms

10 dc-svl-dc1--sfo-dc1-pos.cenic.net (137.164.22.34) 3.923 ms 3.812 ms 3.674 ms

11 te2-3--480.tr01-plalca01.transitrail.net (137.164.131.253) 3.854 ms 4.300 ms 3.958 ms

12 bb1-g1-0.pxpaca.sbcglobal.net (198.32.176.112) 4.543 ms 4.463 ms 4.559 ms

13 151.164.93.249 (151.164.93.249) 68.968 ms 68.869 ms 69.440 ms

14 dist1-vlan30.lgtpmi.ameritech.net (65.42.245.97) 69.434 ms 69.213 ms 68.944 ms

15 rback1-g1-0.lgtpmi.sbcglobal.net (65.42.245.230) 68.845 ms 69.043 ms 69.145 ms

16 adsl-68-22-232-254.dsl.lgtpmi.ameritech.net (68.22.232.254) 823.731 ms 856.567 ms 822.425 ms

17 adsl-68-22-232-249.dsl.lgtpmi.ameritech.net (68.22.232.249) 858.838 ms 890.727 ms 859.053 ms

Traceroute: to aland.bbn.com


DOCS Architecture: Overview

ACK: NSF FIND Program, Dan Blumenthal, Nick McKeown, and John Bowers

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Why DOCS? (or DCS)

• Emerging (video-enabled) applications:– Video downloads– Massively multiplayer games– Video collaborations– Telepresence– IPTV– Applications on a wire, etc.

• If you are happy with the PMO of our networks:– slow downloads– jittery streaming– unreliable audiothen DOCS is not for you.


DOCS Architecture – Physical Aspects

• Circuit switches are suitable to optics (McKeown et al.)– Require no packet processing or buffering

• Circuit switches are simple– Requires about 90% less hardware than an equivalent packet switch– More attractive than equivalent packet switches:

• About eight times the capacity of a packet switch• Five times the capacity per watt• Cost one quarter of the price of the equivalent packet switch.

– Simplest way to build a circuit switch is to “Start with a packet switch and throw most of it away” [Pablo-HotNets-I 2002, IEEE MICRO 2002, JON 2003]

• Circuit switches perform well– Fast restoration times (less than 50 ms)– Contain less software than equivalent routers– Good service guarantees: no queuing delay (so predictable packet

delays), and guaranteed bandwidth

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DOCS: Basic Premise

• DOCS = Dynamic Optical Circuit Switching

• Approach:– Bursty (packet) traffic generated by users/applications– Aggregate traffic at the network edge– Establish high-bandwidth pipes between edge nodes

through the network core– DOCS offers bandwidth-on-demand capabilities to

applications (users can “dial” for bandwidth)

• Example Applications:– Real-time download (say within 5 sec)– Database/website backup (say between 1 am – 3 am,

and not to exceed a 15-min duration)


New Trends for Future Telecom Backbone Networks

• Emergence of new bandwidth-hungry applications:– Scientific grid-computing applications– Consumer applications: Video-on-Demand (VoD), IPTV, …

• Emerging services that require dynamism and flexibility:– Flexible bandwidth reservation, e.g., Bandwidth on Demand

(dial for bandwidth), Advanced reservations, …– Service guarantees (guaranteed bandwidth, fast switching/

restoration times, SLA, availability)

• Increasing gap between optical and electronic transmission and processing speeds

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DOCS Example Applications - DDRs

• DDR = Deadline-Driven Request• Real-time file download

– maximum transfer time a person can tolerate (perhaps 5 sec)

• Database/website/server backup: scheduled at any time, perhaps during night, but with a fixed deadline (completion time)

– flexible application requiring high bandwidth, but not necessarily instantaneously.

• Our research: Provision DDRs in a DOCS network from two perspectives:

– Time dimension: allows flexibility w.r.t. when to when to schedule the request.

– Transmission bandwidth (rate) dimension: allows flexibility (adjustable to network state) w.r.t. data rate to be allocated to the request.


Ethernet is a success story in Local Area Networks (LAN)About 90% of LANs use Ethernet.

Extending its reach from LAN into Metro Area Networks (MAN) has already been established.

Focus now is to extend Ethernet into carrier core networks.Future mode of operation: Ethernet over WDM native Ethernet frames directly over WDM.

Elimination of several layers of other technologies.CapEx and OpEX savings.

Connection-oriented Ethernet.Forwarding: VLAN-XC, Provider Backbone Transport (PBT), T-MPLS.

Following requirements must be taken into account: High resilience.Long reach: 1500- 4000 km.Rates of up to 100 Gbit/s Ethernet (GbE).High degree of mesh.

Ethernet Everywhere

ACK: Siemens (NSN)

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Transmission Rates

Ethernet Rates:100 Gbit/s Ethernet.

Max possible CapEx savings.

Constraint: Signal transmission range for a certain rateSignal’s quality depends on the physical impairments.Transmission Range = Signal traveled distance after which signalquality degrades to a level that it needs regeneration.

Transmission Ranges:Range of 10 Gbit/s signal = 3000 Km.Range of 100 Gbit/s signal = 500 Km.

Etherpath = Lightpath carrying Ethernet frames.


Telecom Nets: “End-to-End” Ethernet?

MetroMetro Long-Haul (Backbone)Long-Haul (Backbone) MetroMetro

Residential

EnterpriseHQ

ISP

Access Technologies

Branch

Branch

VoD/HDTV

Data Center

InternetInternet

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TE vs. NE vs. NP

• Traffic Engineering (TE)

• Network Engineering (NE)

• Network Planning (NP)

• TE – online, dynamic, provisioning problem, ms time scale

• NE – intermediate problem, months time scale

• NP – offline, static, dimensioning problem, 5-yr time scale

– “Put the traffic where the bandwidth is”

– “Put the bandwidth where the traffic is”

– “Put the bandwidth where the traffic is forecasted to be”


Robust Network Design

TTR

0 tTime

Fault occurs Fault fixedConnection arrival

……

Connection departure

……Network Events:

Network Architecture Needs:• More dynamism / flexibility / agility / automation …• Handle multiple (near-simultaneous) faults efficiently• Reprovision (backup) capacity when “network state” changes

– Efficiency tradeoff: bandwidth vs. implementation

• Is a service path “ahead” or “behind” the contract (SLA)?– Reprovision, if necessary; role of penalty and economics in SLA

• Utilize “excess capacity”?• …

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Further Reading

Broadband Access• PONs• WDM in PONs – IEEE Photonics in Switching Conf. (PIS) , Aug. 07• Long-Reach Broadband Access – stay tuned• Hybrid wireless-optical access – JLT, Nov. 07; OFC’07; ICC’07, …• Metro: The vanishing breed?

Backbone Networks• DOCS (“dial for bandwidth”) – PIS, Aug. 07• Robust Network Design – Lots of literature• Ethernet Everywhere – OFC’07 PD paper; GB’07; JLT, Jan. 08


Extra Slides

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What Is An Optical Network?

• It is NOT NECESSARILY all optical” ” ” ” packet switched

• Characteristics of an optical network– Transmission: optical– Switching: could be optical, could be electronic, could be hybrid

could be circuit, could be packet, could be burst

• Most Promising Approach Today– Electronic circuit switching with sub-lambda granularity (STS-1, STS-3, …)

• Example Utility for IP Networking– Connect any two IP routers (geographically far apart) with a direct

(“virtual”) bandwidth pipe… of whatever capacity (STS-1, … , STS-192)– Increase (or decrease or delete) the capacity on demand– Dynamically control the “topology” connecting the IP routers– Create a “separated control network” (of whatever bandwidth)– …


Resilient Mesh Net --Overview

s di

Working

Backup

• Multi-path routing– How many paths?– State-dependent path capacities– Virtual concatenation (VC)

(“traffic grooming”)

1sdp

bsdp

3sdp

2sdp

• Survivable Routing– Primary + backup path(s)– Precomputed backup (?)– Shared backup (?)– Need reliable path (five-9’s)

• Component/link availability

– Need fast recovery

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Data over (Next-Gen) SONET/SDH

Ethernetport GFP VC

LCASEthernet

portGFPVCLCAS

SONET/SDH-enabled optical transport

network

GbE GbE

SONET/SDHframer/mapper

SONET/SDHframer/mapper

STS-3c-7v

7 STS-3c’s

STS-3c-7vSource Destination

• Inverse multiplexing• Relaxing time-slot contiguity/alignment• Reassembly and jitter control


Next-Gen SONET Chip Availability

Source: Light reading

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Problem StatementProblem Statement

• Given:– Network topology G (V, E, C(e, w))– Basic time-slot component, e.g., VT1.5, STS-1, STM-1, etc.– A high-speed request R with bandwidth requirement B. – An inverse-multiplexing control parameter K for maximal

allowed path number.

• Find:

– m distinct paths, where 1 ≤ m ≤ K, such that the aggregated capacity they offer ≥ B.


Implication to Service Resilience

• Route splitting enables degraded services– Ethernet service: peak rate 600 Mbps, guaranteed rate

300 Mbps (against single network-element failure)– Need LCAS

Source

Destination

LCAS

300 Mbps

300 Mbps

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Motivation:Critical Infrastructure Survivability

• Overloads, Attacks, and Failures:– What’s the difference? It’s a “Race against Time”

• “Our society depends on critical infrastructures for delivery of essential services.

• “Telecom, banking, power supply, public transport, etc. increasingly rely on information infrastructures… not only for management and control… but also for monitoring outages and recovery.

• “Combinations of wireless, ad hoc, and fixed networks are becoming a reality in many domains.”

• Tomorrow's networks face the survivability challenge:– how to deliver critical services in a timely manner in

presence of overloads, attacks, and failures?


Modeling “Disasters”

• Define SRGs (shared-risk groups)– for (potentially) correlated failing components– e.g., links + nodes in close geographical proximity

• SRLG (shared-risk link group)– Special case of SRG– Quite common since fibers are laid in ducts, and

duct cuts are more frequent than we wish

• Extend link models (or develop new models) to apply to SRGs

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Which Method?

• PREV: Provisioning fast REstorable VCG– One backup path per node

pair

s di

Working

Backup

1sdp

bsdp

3sdp

2sdp

• PIVM: Protecting Individual VCG Member– One working VCG per

connection– One backup VCG per

working VCG member

s d

1wp

1,1bp

2wp

2,2bp

1,2bp

i

WorkingBackup

telecom optical networks: the road aheadoptical networks: the road ahead biswanath mukherjee child...

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